Concrete Estimator - Sonotube & Post Footings

Cylindrical Foundation & Sonotube Concrete Metrology (ACI 318)

Cylindrical post footing volume follows the geometric cylinder formula:

• Radius (ft) = Diameter (in)24

• Volume (cu ft) = π × r^2 × Depth (ft) × Number of Tubes

• Cubic Yards (yd^3) = Volume (cu ft)27

Pre-Mix Concrete Bag Yields

• 80 lb Bag: Yields approximately 0.60 cu ft (45 bags per cubic yard)

• 60 lb Bag: Yields approximately 0.45 cu ft (60 bags per cubic yard)

• 50 lb Fast-Setting Bag: Yields approximately 0.375 cu ft (72 bags per cubic yard)

Standard Sonotube Sizing Chart (4-Foot Frost Depth Pier)

• 8" Tube × 4 ft: = 1.40 cu ft = 0.052 yd^3 = 3 bags (80 lb)

• 10" Tube × 4 ft: = 2.18 cu ft = 0.081 yd^3 = 4 bags (80 lb)

• 12" Tube × 4 ft: = 3.14 cu ft = 0.116 yd^3 = 6 bags (80 lb)

• 16" Tube × 4 ft: = 5.59 cu ft = 0.207 yd^3 = 10 bags (80 lb)

• 18" Tube × 4 ft: = 7.07 cu ft = 0.262 yd^3 = 12 bags (80 lb)

• 24" Tube × 4 ft: = 12.57 cu ft = 0.465 yd^3 = 21 bags (80 lb)

How to Use This Calculator

Enter your Tube Diameter (Inches) (e.g. 10), Tube Depth / Height (Feet) (e.g. 4), Tube Depth (Inches) (e.g. 0), Number of Tubes / Piers (e.g. 4), Waste & Spillage Allowance (%) — choose from 0% (Exact Geometric Volume), 5% (Smooth Cardboard Tube Forms), 10% (Recommended Sonotubes & Overfill), and Concrete Price per Cu Yard () (e.g. 145.00). Measure twice before entering dimensions — small measurement errors scale up significantly in material estimates.

The Formula

Cylindrical Volume = PI r^2 h

Pre-mix bag yields: 80 lb = 0.60 cu ft, 60 lb = 0.45 cu ft

Worked Example

Pouring a single 12" diameter × 4 ft deep Sonotube pier requires 3.14 cu ft of concrete (6 bags of 80 lb Quikrete).

Understanding Your Result

Always add a 10–15% waste factor to concrete volume estimates for normal pours, and 15–20% for irregular forms or slabs with cutouts. Standard ready-mix concrete is ordered in cubic yards (1 cubic yard = 27 cubic feet). Minimum slab thickness recommendations: driveways 4 inches, garage floors 4–6 inches, structural slabs per engineer specification. Over-ordering concrete is generally preferable to under-ordering — a short pour creates a cold joint that weakens the structure.